1. Field of the Invention
This invention relates to a system and method for preventing false back pressure faults caused by the replacement of particulate filters that trap particulate matter in exhaust gases of an engine.
2. Background Art
Particulate trap filters are provided in engine exhaust systems to filter particulates and soot from exhaust gases. For example, diesel exhaust gases must be cleaned in a particulate filter before being vented to the atmosphere to conform to environmental regulations.
Back pressure in an exhaust system may increase due to increased restriction caused by the accumulation of particulates in the particulate filter. Excessive back pressure may cause damage to the engine or decrease engine performance. Sensors may be used to measure the back pressure to avoid damage to the engine. An operator may be signaled to check the engine or particulate filter when the back pressure exceeds a predetermined level. The particulate filter may then be removed and replaced or regenerated to reduce back pressure to an acceptable level.
New particulate filters when initially installed in the exhaust system of an engine may exhibit excessive back pressure for a limited period of time, i.e. over a “break in” period for the filter. When the new particulate filter is installed, increases in back pressure relating to the new filter flow properties may result in confusion as to whether the new filter is functioning property and may result in unnecessary service inquiries. When an operator observes illumination of a check engine light (“CEL”) or service now light (“SNL”) that is diagnosed as having been caused by high back pressure fault, the operator may believe that the service was not properly performed or that the particulate filter is not functioning properly. False back pressure faults may also occur with new engines and may result in unnecessary customer complaints, service calls and warranty expense.
There is a need for a method and system for monitoring exhaust filter back pressure that does not provide false indications of excessive back pressure after a new particulate filter is installed in the exhaust system. A system and method are needed that can be adapted to and used with a variety of different types and sizes of engines and in a variety of operating conditions.